MULTIFOCAL OPHTHALMIC LENS HAVING REDUCED GHOSTING
An ophthalmic lens, comprising at least one optic including a first zone and a second zone having a second zone. The lens configured such that, when the lens is applied to an average eye, for objects located between infinity and a near focal plane of the average eye, an MTF of the eye's optical system has no phase reversals.
1 . An ophthalmic lens, comprising:
at least one optic including a first zone and a second zone having a second zone,
the lens configured such that, when the lens is applied to an average eye, for objects located between infinity and a near focal plane of the average eye, an MTF of the eye's optical system has no phase reversals.
2 . The lens of claim 1 , wherein the lens is an intraocular lens.
3 . The lens of claim 1 , wherein the lens comprises an anterior surface and a posterior surface, and each of the anterior surface and the posterior surface have at least two zones.
4 . The lens of claim 1 , wherein the zones are concentric.
5 . The lens of claim 1 , wherein the lens has no phase reversal for objects having a spatial frequencies in a range 0-50 lp/mm.
6 . The lens of claim 5 , wherein the lens has no phase reversal for objects having a spatial frequencies in a range 0-75 lp/mm.
7 . The lens of claim 6 , wherein the lens has no phase reversal for objects having a spatial frequencies in a range 0-100 lp/mm.
8 . The lens of claim 1 , wherein the near focal plane is located 1 meter or closer to the front of the average eye.
9 . The lens of claim 8 , wherein a far focal plane of the lens is adapted to provide the average eye with vision at an infinite distance from the eye.
10 . The lens of claim 1 , wherein the near focal plane is located 65 centimeters or closer to the front of the eye.
11 . The lens of claim 10 , wherein a far focal plane of the lens is adapted to provide the average eye with vision at an infinite distance from the eye.
12 . The lens of claim 1 , where in the lens comprises a third zone.
13 . The lens of claim 12 , wherein each of the three zones has a different focal length.
14 . The lens of claim 13 , wherein the MTF has no phase reversals in a range between a focus of the first zone and a focus of the second zone.
15 . The lens of claim 14 , where the MTF has a phase reversal between a focus of the third zone and the range.
16 . The lens of claim 15 , wherein the lens is a single element lens.
17 . A method of designing a multizonal lens using a model eye including the lens, comprising:
optimizing the lens such that second derivatives of a wavefront at an exit pupil of the model eye optical system are substantially zero.
18 . The method of claim 17 , wherein lens comprises a first zone having a first focal length and a second zone having a second wavelength.
19 . The method of claim 18 wherein, when the lens is applied to an average eye, the first focal length provides a first focal plane located 1 meter or closer to the front of an the eye and the second focal length provides a second focal plane at infinity.
20 . The method of claim 17 , wherein the step of optimizing comprises using even aspheric terms of at least one of an anterior surface and a posterior surface of the lens as variables.
21 . The method of claim 17 , further comprising a step of designing a first zone for vision at a near focal plane, and a step of designing a second zone for vision at a far focal plane, both step being performed prior to the step of optimizing the lens.